1. Field of the Invention
This invention relates to latex articles and methods of making the same. In particular, the present invention provides improved powder-free latex gloves and methods for making such gloves, whereby the end product overcomes the natural tackiness of latex and the natural friction of the rubber surface.
2. Background
The majority of latex rubber gloves are powdered to accomplish two objectives: (1) to overcome the natural tackiness of the rubber and allow the gloves to be made without the opposite surface sticking together; and (2) to facilitate donning by overcoming the natural friction of the rubber surface against the hand. However, powder is inconvenient and can contaminate hands and clothing. Also, the powder can interfere with test results when the gloves are worn by technicians performing medical and industrial test procedures. Further, to sensitive individuals, the powders used can be hand irritants. Because powders absorb some of the naturally occurring proteins from the latex and can release these proteins into the air, they can also cause anaphylactic reactions in very sensitive individuals.
Many attempts have been made to produce powder-free, yet easily usable latex gloves. One method used to produce such gloves is to chemically treat the gloves with a solution containing free halogen (chlorine, bromine or fluorine) (see Pendle, TD and Gorton, ADT, "Dipping with natural rubber latex," NR technical bulletin, The Malaysian Rubber Producers' Research Association, Hertford, England (1980), the contents of which are incorporated fully herein by this reference). The halogen reacts with the latex surface, substituting a hydrogen atom on the rubber molecule (polyisoprene) with the halogen. This causes the surface to become more dense and harder, which in turn reduces the natural tackiness and friction, allowing the glove to be donned without additional powder. Typically, the halogen is applied either while the gloves are on the dipping form or mold or after the semi-cured glove has been removed from the dipping form or mold. The halogen is either introduced directly into the aqueous treating solution or may be generated by the dissolution of a halogen-containing solution (e.g., sodium hypochlorite) into water, with the subsequent addition of acid (e.g., HCl) to release the free halogen into the solution.
Other methods have entailed coating the latex surface with another polymer (e.g., hydrogel or polyurethane) which imparts a lower coefficient of friction to the surface.
It is, therefore, highly desirable to produce a substantially if not totally powder-free article, such as a rubber glove, that overcomes the natural tackiness of the rubber and, in the case of gloves, condoms, etc. facilitates donning by overcoming the natural friction of the rubber surface against human skin. It is also highly desirable to provide a method of treating latex articles that avoids the necessity of turning articles inside-out during treatment. Moreover, it is highly desirable to provide a processing method that does not contain contaminants. In addition, it is highly desirable to provide a method of treating a latex article, such as a glove, that produces an article that overcomes the natural tackiness of the rubber and, for donnable articles, facilitates donning without releasing powders or other substances that can irritate sensitive individuals.